US20220145589A1 - Hydraulic system and methods for an earthmoving machine - Google Patents
Hydraulic system and methods for an earthmoving machine Download PDFInfo
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- US20220145589A1 US20220145589A1 US17/093,120 US202017093120A US2022145589A1 US 20220145589 A1 US20220145589 A1 US 20220145589A1 US 202017093120 A US202017093120 A US 202017093120A US 2022145589 A1 US2022145589 A1 US 2022145589A1
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/26—Indicating devices
- E02F9/264—Sensors and their calibration for indicating the position of the work tool
- E02F9/265—Sensors and their calibration for indicating the position of the work tool with follow-up actions (e.g. control signals sent to actuate the work tool)
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/283—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets with a single arm pivoted directly on the chassis
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
- E02F3/422—Drive systems for bucket-arms, front-end loaders, dumpers or the like
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/28—Dredgers; Soil-shifting machines mechanically-driven with digging tools mounted on a dipper- or bucket-arm, i.e. there is either one arm or a pair of arms, e.g. dippers, buckets
- E02F3/36—Component parts
- E02F3/42—Drives for dippers, buckets, dipper-arms or bucket-arms
- E02F3/43—Control of dipper or bucket position; Control of sequence of drive operations
- E02F3/431—Control of dipper or bucket position; Control of sequence of drive operations for bucket-arms, front-end loaders, dumpers or the like
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2203—Arrangements for controlling the attitude of actuators, e.g. speed, floating function
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2217—Hydraulic or pneumatic drives with energy recovery arrangements, e.g. using accumulators, flywheels
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2225—Control of flow rate; Load sensing arrangements using pressure-compensating valves
- E02F9/2228—Control of flow rate; Load sensing arrangements using pressure-compensating valves including an electronic controller
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2246—Control of prime movers, e.g. depending on the hydraulic load of work tools
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2264—Arrangements or adaptations of elements for hydraulic drives
- E02F9/2267—Valves or distributors
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B13/00—Details of servomotor systems ; Valves for servomotor systems
- F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
- F15B13/024—Pressure relief valves
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/08—Superstructures; Supports for superstructures
- E02F9/0841—Articulated frame, i.e. having at least one pivot point between two travelling gear units
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2285—Pilot-operated systems
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2296—Systems with a variable displacement pump
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
- F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
- F15B11/161—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load
- F15B11/165—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors with sensing of servomotor demand or load for adjusting the pump output or bypass in response to demand
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/20507—Type of prime mover
- F15B2211/20523—Internal combustion engine
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/20—Fluid pressure source, e.g. accumulator or variable axial piston pump
- F15B2211/205—Systems with pumps
- F15B2211/2053—Type of pump
- F15B2211/20546—Type of pump variable capacity
- F15B2211/20553—Type of pump variable capacity with pilot circuit, e.g. for controlling a swash plate
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/50—Pressure control
- F15B2211/505—Pressure control characterised by the type of pressure control means
- F15B2211/50509—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means
- F15B2211/50536—Pressure control characterised by the type of pressure control means the pressure control means controlling a pressure upstream of the pressure control means using unloading valves controlling the supply pressure by diverting fluid to the return line
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6054—Load sensing circuits having valve means between output member and the load sensing circuit using shuttle valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/605—Load sensing circuits
- F15B2211/6051—Load sensing circuits having valve means between output member and the load sensing circuit
- F15B2211/6055—Load sensing circuits having valve means between output member and the load sensing circuit using pressure relief valves
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/633—Electronic controllers using input signals representing a state of the prime mover, e.g. torque or rotational speed
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/63—Electronic controllers
- F15B2211/6303—Electronic controllers using input signals
- F15B2211/6343—Electronic controllers using input signals representing a temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
- F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
- F15B2211/00—Circuits for servomotor systems
- F15B2211/60—Circuit components or control therefor
- F15B2211/665—Methods of control using electronic components
- F15B2211/6652—Control of the pressure source, e.g. control of the swash plate angle
Definitions
- the present disclosure relates generally to hydraulic systems and methods, and more particularly, to a hydraulic system and methods for an earthmoving machine.
- Earthmoving machines such as wheel loaders, motor graders, excavators, and dozers, are commonly used in material moving applications, including mining, road maintenance, surface contouring, etc.
- the vehicles often include hydraulic systems to provide functionality and/or control various aspects of the machines, such as hydraulically-powered articulation joints, hydraulically-powered traction devices, and hydraulically powered implements, such as buckets, shovels, and blades.
- a prime mover for example a diesel, gasoline, or gaseous fuel-powered internal combustion engine, drives dedicated steering and implement pumps that provide hydraulic power to the steering components and the implements.
- EGR exhaust gas recirculation
- DPF diesel particulate filter
- the accumulation of particulate matter may result in increased back pressure on the prime mover.
- the drive system requires periodic regeneration, for example, to burn off particulate matter that has accumulated in the drive system.
- the regeneration may promote oxidation (e.g., burning off) of the particulate matter on the filter with heat from engine exhaust.
- an exhaust temperature of the engine may not be hot enough to provide regeneration.
- the machine may encounter difficulties in performing the regeneration in cold ambient temperature conditions (e.g., below freezing) and/or when there is a low load on the engine.
- U.S. Pat. No. 7,467,033, issued to Miller et al. on Dec. 16, 2008 (“the '033 patent”) describes a method of controlling an engine to maintain a calibrated minimum load for the engine.
- the method of the '033 patent involves a minimum engine torque adder that is calibrate as a torque ramp rate to adjust the allowable torque limit that is added to the engine torque if the measured engine load is near the calibrated minimum engine load for a given engine speed.
- the method of the '033 patent may help to maintain engine fuel combustion stability and avoid undesirable engine exhaust gas temperatures during prolonged engine operation at low load. While the control method of the '033 patent may help maintain a calibrated minimum load on an engine, the added load on the engine via the torque added may not be desirable under certain conditions.
- a hydraulic system for a machine may include an implement pump, a valve, and an implement valve subsystem.
- the implement pump may include a load sensing control, and the valve may control the flow of hydraulic fluid to the implement pump.
- the implement valve subsystem may include one or more implement control subsystems to control movement of an implement.
- the valve may be an electrohydraulic proportional relief valve and may include a solenoid configured to adjust the pressure of hydraulic fluid delivered to the implement pump proportionally to a current delivered through the solenoid.
- a method of operating a hydraulic system for a machine may include, in response to a regeneration cycle for a particulate filter in an after-treatment system for an engine, detecting one or more of an ambient temperature, a temperature of the exhaust of the engine, or a load demand on the engine.
- the method may also include, in response to one or more of the ambient temperature, the temperature of the exhaust of the engine, or the load demand on the engine being below respective threshold values, delivering current through a solenoid of an electrohydraulic valve.
- the electrohydraulic valve may control a flow of hydraulic fluid to an implement pump, and the current through the solenoid may cause the electrohydraulic valve to open and deliver hydraulic fluid to the implement pump to upstroke the implement pump.
- the implement pump may control an implement and may include a load sensing control configured to increase the pressure demand on the implement pump in response to the delivery of hydraulic fluid.
- the increase pressure demand on the implement pump may be configured to increase the power demand on the engine.
- an earthmoving machine may include an engine, an implement, and a hydraulic system.
- the hydraulic system may include an implement pump and an electrohydraulic valve.
- the implement pump may be powered by the engine and may be configured to drive the implement, and the implement pump may include a load sensing control.
- the electrohydraulic valve may control the flow of hydraulic fluid to the load sensing control of the implement pump.
- the electrohydraulic valve may include a solenoid configured to adjust the pressure of hydraulic fluid through the electrohydraulic valve proportionally to a current delivered through the solenoid.
- FIG. 1 is an illustration of an exemplary machine according to aspects of the disclosure.
- FIG. 2 is a schematic of an exemplary hydraulic system of the machine of FIG. 1 .
- FIG. 3 provides a flow chart depicting an exemplary method for controlling the hydraulic system of the machine.
- FIG. 4 provides a flow chart depicting an exemplary method for calibrating one or more aspects of the hydraulic system of the machine.
- FIG. 5 illustrates a graph of the current command and the power command formed during the calibration of one or more aspects of the hydraulic system of the machine.
- FIG. 1 depicts an exemplary machine, for example, a wheel loader 10 .
- wheel loader 10 may be any of the types of machines described above.
- Wheel loader 10 includes a machine body 12 , which may include an operator station, an engine housing, and a prime mover or an engine 100 .
- Engine 100 may be a diesel engine, and may be coupled to an after-treatment system 102 .
- an exhaust line from engine 100 may be coupled to after-treatment system 102 .
- After-treatment system 102 may include a diesel oxidation catalyst (“DOC”) 104 and a particulate filter 106 (e.g., a diesel particular filter or a DPF).
- Wheel loader 10 may also include an implement assembly 14 .
- DOC diesel oxidation catalyst
- Implement assembly 14 may include an arm 16 , a linkage 18 , and a bucket 20 .
- Bucket 20 may be coupled to an end of arm 16 .
- bucket 20 may also be a different work implement, such as a fork, grapple, etc., and, in some aspects, the work implement may be interchangeable.
- Linkage 18 may have one or more degrees of freedom.
- Wheel loader 10 may include ground surface engaging devices, such as wheels 21 that support machine body 12 and are powered by engine 100 . Although a wheeled machine is shown and described, one skilled in the art will appreciate that other machines, including track-type machines, may also be utilized.
- FIG. 1 also shows wheel loader 10 with a first, lowered configuration (solid lines) of implement assembly 14 and with a second, raised configuration (dashed lines) of implement assembly 14 .
- Lift actuator 22 may include, for example, a hydraulic fluid cylinder actuator or any other type of actuator, as would be apparent to one skilled in the art.
- One or more lift pressure sensors 24 may be configured to measure forces within the actuator 22 , or on another component of lift actuator 22 , and may be force sensors.
- the tilt of bucket 16 may be powered and controlled by a tilt actuator 26 .
- Tilt actuator 26 may include, for example, a hydraulic fluid cylinder actuator or any other type of actuator, as would be apparent to one skilled in the art.
- One or more tilt pressure sensors 28 may be configured to measure forces within tilt actuator 26 , or on another component of tilt actuator 26 , and may be force sensors.
- lift pressure sensors 24 and tilt pressure sensors 28 may be disposed in/on a head end and a rod end of lift actuator 22 and tilt actuator 26 , respectively.
- lift pressure sensors 24 and tilt pressure sensors 28 may be disposed in other locations relative to an actuator, such as within a hydraulic circuit associated with an actuator (e.g., one or more of control subsystems 208 a - 208 c , FIG. 2 ).
- Forces acting on lift and/or tilt cylinder 22 , 26 may include a head-end pressure and/or a rod-end pressure on each side of a piston of the actuator.
- Lift pressure sensors 24 and tilt pressure sensors 28 may be configured to measure one or both of head-end and rod-end pressures of the lift and tilt cylinders, respectively.
- lift pressure sensors 24 and tilt pressure sensors 28 may be configured to measure a net force acting on a lift or tilt cylinder, respectively.
- Lift pressure sensors 24 and tilt pressure sensors 28 may detect pressure of fluid within their respective actuator. Force or pressure information may also be derived from other sources, including other sensors.
- wheel loader 10 may include one or more additional sensors, for example, an arm position sensor 32 and a bucket position sensor 34 .
- Arm position sensor 32 may gather data indicative of a position of arm 14 , including for example, an angle, a height or an extension of arm 14 .
- Bucket position sensor 34 may gather data indicative of a position of bucket 16 , including, for example, a height, lateral location, and/or tilt of bucket 16 .
- wheel loader 10 may include one or more additional sensors, inertial measurement units, etc.
- controller 30 may be in communication with one or more features of wheel loader 10 and receive inputs from and send outputs to, for example, one or more user interfaces in the cab or remote from wheel loader 10 .
- wheel loader 10 may include electrohydraulic and/or hydro mechanical hydraulic systems, and controller 30 may control one or more electrical switches or valves in order to control one or more hydraulic cylinders, actuators, or electrical elements in order to operate wheel loader 10 .
- controller 30 may include one or more controllers each associated with one or more components or systems of wheel loader 10 .
- controller 30 may be in communication with a valve 204 and/or an implement pump 206 ( FIG. 2 ) for controlling aspects of valve 204 and/or implement pump 206 , which may control aspects of engine 100 (e.g., a load command, a temperature of the output exhaust, etc.), as further detailed below.
- a valve 204 and/or an implement pump 206 FIG. 2
- engine 100 e.g., a load command, a temperature of the output exhaust, etc.
- Engine 100 may be configured to generate and transmit power to wheels 21 , for example, via a transmission (not shown).
- Engine 100 may include an internal combustion engine that produces mechanical and/or electrical power output.
- engine 100 may be a four-stroke diesel engine.
- engine 100 may be coupled to after-treatment system 102 , which may include diesel oxidation catalyst (“DOC”) 104 and particulate filter 106 .
- Engine 100 may include one or more subsystems, for example, a fuel system, an air induction system, an exhaust system (coupled to after-treatment system 102 ), a lubrication system, a cooling system, and/or the like.
- Engine 100 may be configured to produce a torque output directed to a transmission and/or to other parasitic loads (e.g., to hydraulic systems (i.e., implement pump 206 ), electrical systems, cooling systems, etc.) through a range of speeds.
- parasitic loads e.g., to hydraulic systems (i.e., implement pump 206 ), electrical systems, cooling systems,
- engine 100 may be coupled to after-treatment system 102 , which may include DOC 104 and particular filter 106 .
- DOC 104 may be the first component (i.e., directly downstream from engine 100 ) of after-treatment system 102 .
- DOC 104 may receive an exhaust flow from engine 100 at an inlet of DOC 104 .
- DOC 104 may be a flow through filter that includes one or more oxidation devices.
- the one or more oxidation devices may include one or more precious metals, and may help to initiate an oxidation of hydrocarbons, carbon monoxide, unburned fuel and oil, etc.
- Particulate filter 106 may be downstream of DOC in after-treatment system 102 .
- Particulate filter 106 may be a wall-flow filter that helps to trap or otherwise collect soot or other particulate material that was not oxidized by DOC 104 .
- Particulate filter 106 may be heated by the exhaust flow from engine 100 , thereby thermally aging or oxidizing the particulate matter deposited in particulate filter 106 when the exhaust flow is of a sufficient temperature. In some instances, for example, when environmental temperatures are low, when torque on the engine is low, etc., the heat from the exhaust flow from engine 100 may not be hot enough to oxidize the particulate material collected by particulate filter 106 .
- after-treatment system 102 may include a selective catalytic reducer (SCR), for example, downstream of particulate filter 106 .
- SCR selective catalytic reducer
- FIG. 2 is a schematic illustration of a portion of a hydraulic system 200 that may control the position and/or movement of an implement, for example, bucket 16 .
- hydraulic system 200 includes a pilot pressure valve 202 , a valve 204 , an implement pump 206 , and an implement valve subsystem 208 .
- Hydraulic system 200 may include a relief valve 210 , for example between portions of valve 204 and implement pump 206 .
- relief valve 210 may be a proportional relief valve, which may allow for the control of the pressure in the hydraulic line connecting a discharge line 206 a of implement pump 206 to valve 204 .
- Hydraulic system 200 may also include a resolver 212 , for example, between portions of valve 204 , implement pump 206 , and implement valve subsystem 208 .
- Resolver 212 may include a hydraulic logic element and may help to maintain consistent pressures between portions, for example, pilot pressure portions, of valve 204 , implement pump 206 , and implement valve subsystem 208 by receiving two pressures and outputting the higher of the two pressures.
- Hydraulic system 200 may also include a margin relief valve 214 , which may be positioned within implement valve subsystem 208 , and may relieve pressure from implement valve subsystem 208 when the hydraulic fluid exceeds a predetermined pressure. Margin relief valve 214 may help to create resistance to the flow of hydraulic fluid driven by implement pump 206 .
- hydraulic system 200 may include one or more pressure sensors 216 , which may detect the pressure of the hydraulic fluid at one or more locations in hydraulic system 200 .
- hydraulic system 200 may include one or more outlets 218 , for example, to return hydraulic fluid to a reservoir tank.
- One or more components of hydraulic system 200 for example, one or more of pilot pressure valve 202 , implement pump 206 , implement valve subsystem 208 , relief valve 210 , pressure sensor 216 , etc., may be in communication (e.g., via a wired or wireless connection) with controller 30 .
- Pilot pressure valve 202 may be any suitable pressure valve, such as, for example, a relief valve, a piston valve, a guided-piston relief valve, a differential-piston relief valve, etc. Pilot pressure valve 202 may provide a release of hydraulic fluid when the internal pressure of hydraulic system 200 exceeds a pressure of approximately 2500 kPa to approximately 4000 kPa, for example, approximately 3800 kPa. Additionally, pilot pressure valve 202 may be coupled to one or more reservoirs (not shown) of hydraulic fluid. In one aspect, pilot pressure valve 202 may be configured to ensure an adjustable pilot pressure for hydraulic system 200 , for example, controlled by controller 30 .
- valve 204 is a directional valve and includes a solenoid 230 .
- wheel loader 10 may be an electrohydraulic machine, and valve 204 may be an electrohydraulic proportional valve.
- Valve 204 may be biased toward a closed configuration, but valve 204 may open when current is delivered through solenoid 230 .
- Valve 204 may be a proportional valve and solenoid 230 may be a proportional solenoid, for example, such that solenoid 230 adjusts and/or regulates flow of hydraulic fluid through valve 204 based on an intensity of an electrical signal (i.e., current), for example, from controller 30 .
- Valve 204 may be a control valve associated with pump 206 .
- valve 204 may be upstream of implement pump 206 , for example, such that output fluid from valve 204 may be delivered to pump 206 , for example, through resolver 212 when the pressure of the hydraulic fluid from valve 204 exceeds the pressure of hydraulic fluid on the opposing side of resolver 212 .
- Implement pump 206 may be a hydraulic pump and may include an integrated load sensing control 232 . As mentioned, implement pump 206 may be powered by engine 100 . Additionally, implement pump 206 may pressurize hydraulic fluid based on a pressure, volume, flow, etc. of hydraulic fluid received at load sensing control 232 . In this aspect, the pressure command on implement pump 206 may be proportional to the current through solenoid 230 , for example, through the relationship between the current through solenoid 230 and the flow of hydraulic fluid through valve 204 . For example, as discussed below, over one or more ranges, the pressure command on implement pump 206 may be substantially linearly correlated to the current through solenoid 230 .
- valve 204 and solenoid 230 may be controlled to add load on engine 100 , for example, during a regeneration cycle. Additionally, over the one or more ranges, the power command on engine 100 may be substantially linearly correlated to the current through solenoid 230 .
- Implement valve subsystem 208 may include one or more subsystems, for example, to control the position of bucket 20 .
- the one or more subsystems may be controlled based on the relative pressures on respective portions of the subsystems.
- implement valve subsystem 208 may include a rack/dump control subsystem 208 a , a lift/lower/float control subsystem 208 b , and one or more auxiliary control subsystems 208 c .
- implement valve subsystem 208 may include an implement valve relief valve 220 , which may be connected to an outlet 222 , for example, to return hydraulic fluid to the reservoir.
- FIG. 3 is a flow chart depicting an exemplary method 300 for controlling hydraulic system 200 .
- wheel loader 10 may perform an operation, for example, moving material from one location to another.
- wheel loader 10 may initiate a regeneration cycle or procedure.
- one or more sensors coupled to controller 30 may detect a build up of particulate material on particulate filter 106 in after-treatment system 102 .
- the regeneration procedure may be initiated after a predetermined amount of operating time for wheel loader 10 since the previous regeneration procedure.
- the regeneration procedure includes increasing the load command on engine 100 such that the exhaust temperature is increased to a certain temperature and/or for a certain duration to help burn off the particulate material on particulate filter 106 in after-treatment system 102 .
- a step 306 may include increasing the load on engine 100 during the regeneration procedure by upstroking implement pump 206 , for example, via one or more components of hydraulic system 200 .
- controller 30 may signal valve 204 to transition from a closed configuration to a more open configuration, for example, by delivering current to solenoid 230 .
- this current through solenoid 230 may deliver more hydraulic fluid to implement pump 206 , which in turn causes implement pump 206 to pump hydraulic fluid at a higher pressure.
- Implement pump 206 pumping the hydraulic fluid at the higher pressure may increase the load demand on engine 100 , as engine 100 powers implement pump 206 .
- the increased load demand on engine 100 may increase the temperature of the exhaust output by engine 100 , which may help to burn off particulate matter on particulate filter 106 in after-treatment system 102 .
- the hydraulic fluid pumped at the higher pressure by implement pump 206 is not used, for example, does not drive any components of implement valve subsystem 208 . Instead, as discussed below, the pressurized fluid may be released through one or more valves and return to a hydraulic fluid tank or reservoir (not shown).
- step 306 may be optional.
- controller 30 may only signal valve 204 to transition to the more open configuration when the temperature at particulate filter 106 is below a certain threshold temperature.
- controller 30 may be coupled to a temperature sensor, for example, at an inlet of particulate filter 106 .
- controller 30 may only signal valve 204 to transition to the more open configuration when the ambient temperature is below a certain threshold temperature.
- controller 30 may be coupled to a temperature sensor on a portion of wheel loader 10 .
- controller 30 may be coupled to one or more of lift pressure sensor 24 , tile pressure sensor 28 , arm position sensor 32 , and/or bucket position sensor 34 .
- Controller 30 may receive one or more signals from these sensors indicative of a position and/or load of bucket 20 , which may be indicative of a pressure demand on implement pump 206 and/or a power demand on engine 100 .
- controller 30 may only signal valve 204 to transition to the more open configuration when one or more of the pressure demand on implement pump 206 and/or the power demand on engine 100 are below certain thresholds, for example, indicating low load conditions.
- step 308 includes ending the regeneration procedure. If step 306 is performed, step 308 includes signaling valve 204 to transition to a more closed configuration, for example, by delivering a lower current (or no current) through solenoid 230 .
- method 300 includes a step 310 , in which wheel loader 10 returns to performing the operation (e.g., moving material).
- Step 310 may include indicating to the user that the regeneration procedure is complete. Nevertheless, it is noted that wheel loader 10 may also be operated during the regeneration procedure.
- Method 300 may also include displaying one or more indications to a user, for example, via a user interface.
- one or more the indications may indicate to the user that wheel loader 10 is undergoing a regeneration procedure, an estimated duration of the regeneration procedure, when the regeneration procedure is complete or nearing completion, etc.
- FIG. 4 is a flow chart depicting an exemplary method 400 for calibrating and/or mapping a relationship of components of hydraulic system 200 .
- method 400 is a method for calibrating and/or mapping a relationship of a signal or current to valve 204 relative to a pressure command on implement pump 206 and, correspondingly, a load command on engine 100 .
- FIG. 5 is a graph of portions of the calibration during method 400 .
- method 400 may include an initial step of entering a calibration mode, for example, automatically and/or based on user input.
- the initial step of entering the calibration mode may be done after the manufacture of wheel loader 10 and during initial calibration of wheel loader 10 , for example, before shipment to a user.
- the initial step of entering the calibration mode may be done while wheel loader 10 is at a work site.
- various aspects of method 400 may depend on the operational conditions of wheel loader 10 and/or surrounding wheel loader 10 , for example, ambient temperatures, work site elevation, bucket load conditions, engine speeds, etc.
- a step 402 includes setting engine 100 at a first engine speed, for example, approximately 800 rotations per minute (“rpm”).
- a step 404 then includes increasing (or ramping up) the current delivered to solenoid 230 , for example, to transition valve 204 to a more open position such that a greater amount of hydraulic fluid and/or a higher pressure of hydraulic fluid is delivered to implement pump 206 .
- Step 404 may include increasing the current to solenoid 230 until a pump discharge pressure (e.g., as measured by pressure sensor 216 ) changes by a certain amount, for example, by approximately 100 kPa.
- the change in the pump discharge pressure may be indicative of the start of an active range for valve 204 , which may be a proportional EH valve. Nevertheless, the change in the pump discharge pressure may not yet indicate the active range over which the current to solenoid controls the overall load add control on engine 100 .
- Method 400 further includes a step 406 , in which the current to solenoid 230 is incrementally increased or ramped up.
- the current to solenoid 230 may be increased by approximately 0.01 amps to approximately 0.02 amps, and may be held at each current level for a period of time, for example, approximately 5 seconds, approximately 10 seconds, approximately 20 seconds, approximately 30 seconds, etc.
- the current to solenoid 230 may be increased by approximately 5% to 10% of the previous current value.
- Each level of current to solenoid may yield a steady state pressure generated by the pump, which may be measured and recorded.
- the incremental increase in the current to solenoid 230 may be performed until the pressure change between consecutive current levels is less than a certain value (e.g., approximately 50 kPa).
- a pressure change between consecutive current levels being less than the certain value may be indicative of implement pump 206 reaching a maximum displacement. At the maximum displacement, the current command, the measured average pump pressure, and the actual engine speed may be recorded.
- the current values and pressure values at the first engine speed may be correlated, for example, graphed, as discussed below with respect to FIG. 5 .
- the commanded current, actual average pump pressure while at the commanded current, and an actual average engine speed may all be recorded for each commanded current level to solenoid.
- the output power (or power command on engine 100 ) may be calculated, for example, using the engine speed and pump pressure.
- the calculation may assume a pump speed to engine speed ratio and a maximum pump displacement based on various system and/or design parameters.
- a pump flow may be calculated based on the pump speed times the maximum pump displacement.
- the pump flow for a given situation may be calculated based on the pressure of hydraulic fluid in discharge line 206 a . For example:
- the pump power may be calculated by the pump flow times the average pump pressure.
- the maximum pump power may equal the pump displacement of 165 cc/revolution times the average pump pressure of 8,000 kPa. Accordingly, if the engine speed is 800 rpm, the output engine power may calculated to be approximately 18 kW. It is noted that this calculation includes multiplying by 1.667 ⁇ 10 ⁇ 8 in order to convert to kilowatts.
- the pump power may calculated by multiplying the torque and the shaft speed.
- method 400 includes a step 408 , in which engine 100 is set to a second engine speed, for example, approximately 1800 rpm. Then, step 406 may be repeated at the second engine speed as a step 410 .
- the current to solenoid 230 may be increased until a pump discharge pressure changes by a certain amount, for example, approximately 100 kPa. The change in the pump discharge pressure may be indicative of the start of an active range for valve 204 , which may be a proportional EH valve. Additionally, the current to solenoid 230 may then be incrementally increased or ramped up, and the pump discharge pressure at each level of current to solenoid 230 may yield a steady state pressure generated by the pump, which may be measured and recorded. Again, the maximum pump flow at the second engine speed may be calculated, and then the engine power may be calculated at the second engine speed.
- the measurements made during of method 400 may be graphed as a current to power calibration curve.
- the two sets of solenoid current commands and the calculated engine power commands (at the two different engine speeds) may be plotted on a graph ( FIG. 5 ), and method 400 may extrapolate a line between the two points to create a current to power calibration curve.
- the current to power calibration curve may be used to correlate a current through solenoid 230 with a power command on engine 100 , and thus a resulting temperature of the exhaust from engine 100 , which may help burn off particulate material on particulate filter 106 . It is noted that the measurements of method 400 and graph of FIG.
- method 400 assumes a substantially linear relationship between the power of implement pump 206 and the current through solenoid 230 . If other or additional components are used, this relationship may not be substantially linear. In this instance, the steps of method 400 may be repeated, for example, in order to obtain additional data points (e.g., third and fourth data points). The data points on the graph of the current through solenoid 230 and the power of implement pump 206 may then be used to determine the relationship. In this aspect, method 400 may be repeated as many times as necessary to obtain data points and determine the relationship between the current through solenoid 230 and the power of implement pump 206 .
- additional data points e.g., third and fourth data points
- FIG. 5 illustrates a graph 500 of an exemplary relationship between the current command (e.g., in amps (“A”)) delivered to solenoid 230 and the power command (i.e., in kilowatts (“kW”)) output by engine 100 , for example, in order to power implement pump 206 .
- the power command may be an additional power command relative to a baseline power command on engine 100 , for example, under idling conditions. As shown, with 0 A delivered to solenoid 230 , engine 100 outputs a power command of 0 kW. As the current is increased, for example, to approximately 1.160 A, the power command increases, for example, to approximately 0.1 kW. This initial increase in power command relative to the increased current command may include a steep slope, as shown by a portion 502 .
- portion 502 may correspond to step 404 .
- the increase in power command relative to the increased current command may include a slope that is less steep, as shown by portion 504 .
- the current command may be increased from approximately 1.160 A to approximately 1.4 A, and the power command on engine 100 may be calculated based on the engine speed and the pressure of hydraulic fluid from implement pump 206 .
- the power command on engine 100 may be approximately 45 kW.
- the current command to solenoid 230 may be increased to approximately 1.9 A, and the resulting power command on engine 100 may be approximately 80 kW.
- the current command may remain at approximately 1.9 A, and the power command may be approximately 100 kW.
- This may be indicative of saturation of the current command at a configurable maximum current value, for example, as shown by portion 506 of graph 500 .
- this may be indicative that implement pump 206 has reached maximum displacement, and thus that no additional power can be achieved.
- this may be indicative that the control valve output pressure has saturated or at a maximum value.
- portions 504 and 506 may correspond to step 406 .
- Engine 100 may then be set to a second engine speed, for example, a maximum engine speed and/or approximately 1800 rpm, corresponding to step 408 .
- step 404 may be repeated, for example, as step 410 , and the current delivered to solenoid 230 may be incrementally increased until a pressure change between consecutive current values is less than a certain value.
- step 410 may include setting the current command at approximately 1.29 A and measuring an engine command of approximately 18 kW.
- setting the current command at approximately 1.56 A may result in a measured engine command of approximately 55.2 kW.
- These measurements may also be plotted in graph 500 . For example, as shown in FIG.
- portion 504 may be substantially linear, illustrating the relationship between the current applied to solenoid 230 and the power command on engine 100 over this active range, corresponding to step 406 of method 400 .
- graph 500 may be used to extrapolate a resulting power command on engine 100 for one or more current commands for solenoid 230 , which may also be used to increase the load on engine 100 , for example, to help burn off particulate material on particulate filter 106 , to help in general retarding (e.g., when wheel loader 10 is traveling down a hill), to help warm up engine 100 or other components of wheel loader 10 , for example, when starting wheel loader 10 in cold ambient temperatures, etc.
- method 400 may be performed, and graph 500 may be formed, in a reverse order.
- a maximum current command may be applied to saturate solenoid 230 with the maximum current, and the actual pump power may be calculated, indicative of portion 506 as discussed above.
- the current command may be incrementally reduced until the pump pressure decreases by a certain amount.
- the current command may be reduced further, and the actual pump power may be determined and plotted, as discussed above to form portion 504 .
- the current command may be reduced further (closer to 0 A), until the pump pressure decreases significantly, indicative of portion 502 .
- these steps may be repeated at a second engine speed.
- the pump pressure decrease may be observed after engine 100 has been set to the second engine speed.
- the current commands on solenoid and resulting actual pump power on engine 100 may be graphed to form a graph similar to graph 500 .
- valve 204 may be incorporated into hydraulic system 200 with minimal modifications of existing hydraulic systems.
- delivery of hydraulic fluid from valve 204 to implement pump 206 causes implement pump 206 to upstroke without a pressure demand from implement valve subsystem 208 .
- the regeneration command, via implement pump 206 may require an increased load command on engine 100 (e.g., increasing the temperature of the exhaust from engine 100 to increase the temperature at particulate filter 106 ) without an implement command.
- valve 204 may be an electrohydraulic valve with solenoid 230 .
- Using valve 204 to deliver hydraulic fluid to implement pump 206 for example, by applying current through solenoid 230 , may cause implement pump 206 to upstroke and demand greater power from engine 100 , even though implement pump 206 or implement valve 208 are not otherwise requesting greater power from engine 100 .
- Additional components of hydraulic system 200 for example, margin relief valve 214 , help to release or dump hydraulic fluid from hydraulic system 200 , which may help to reduce the overall pressure, generate a flow restriction for hydraulic fluid, and/or increase the pressure on implement pump 206 and the power demand on engine 100 , without inadvertently delivering high pressure hydraulic fluid to implement valve subsystem 208 or individual subsystems 208 a - 208 c .
- the pressure demand on implement pump 206 and thus the power demand on engine 100 , may be proportional to the current applied through solenoid 230 of valve 204 .
- the increase power demand on engine 100 may increase the temperature of exhaust from engine 100 , which may help perform or expedite a regeneration cycle to burn off or otherwise remove particulate material on particulate filter 106 of after-treatment system 102 , for example, when wheel loader 10 is in cold ambient temperature conditions and/or there is a low load on engine 100 .
- the strategy to increase the power demand on engine 100 discussed herein may also be used in other circumstances. For instance, the strategy to increase the power demand on engine 100 may be used for general retarding, for example, while wheel loader 10 is traversing a steep down grade and additional load on engine 100 is required.
- the strategy to increase the power demand on engine 100 may be used to help warm up engine 100 and/or other elements (e.g., hydraulic system 200 ) of wheel loader 10 , for example, when starting wheel loader 10 in cold ambient temperature conditions.
- the calibration methods discussed herein may allow for a user and/or controller 30 to extrapolate a relationship between current commands on solenoid 230 and the resulting power command on engine 100 .
- a determined range i.e., portion 504
- increasing the current through solenoid 230 increases the flow of hydraulic fluid to implement pump 206 , which proportionally increases a pressure demand on implement pump 206 , creating a proportional power command on engine 100 .
- the temperature of exhaust output from engine 100 may be increased without otherwise moving other components of wheel loader 10 .
- this procedure may be performed by controller 30 , thus reducing or eliminating a need for user intervention during a regeneration cycle.
- controller 30 may determine the range of portion 504 .
- Controller 30 may then selectively deliver current through solenoid 230 during a regeneration cycle to control the output pressure of implement pump 206 , and thus control the load demand on engine 100 and increase the temperature of exhaust output from engine 100 during the regeneration cycle, for example, when wheel loader 10 is in cold ambient temperature conditions and/or there is a low load on engine 100 . Based on the calibration, controller 30 may deliver an appropriate or necessary amount of current to solenoid 230 to increase the power command on engine 100 as appropriate or needed, for example, in order to increase the temperature of the exhaust from engine 100 and correspondingly increase the temperature at particulate filter 106 .
- controller 30 may be coupled to one or more temperature sensors, along with lift pressure sensor 24 , tilt pressure sensor 28 , arm position sensor 32 , bucket position sensor 34 , etc., and may thus determine when temperature and/or load conditions necessitate performing method 300 during a regeneration cycle.
- hydraulic system 200 , method 300 , and method 400 may be used on any machine having integrated hydraulic systems. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
Abstract
Description
- The present disclosure relates generally to hydraulic systems and methods, and more particularly, to a hydraulic system and methods for an earthmoving machine.
- Earthmoving machines, such as wheel loaders, motor graders, excavators, and dozers, are commonly used in material moving applications, including mining, road maintenance, surface contouring, etc. To effectively accomplish tasks associated with these applications, the vehicles often include hydraulic systems to provide functionality and/or control various aspects of the machines, such as hydraulically-powered articulation joints, hydraulically-powered traction devices, and hydraulically powered implements, such as buckets, shovels, and blades. A prime mover, for example a diesel, gasoline, or gaseous fuel-powered internal combustion engine, drives dedicated steering and implement pumps that provide hydraulic power to the steering components and the implements.
- These machines often include exhaust gas recirculation (“EGR”), in which emissions from the engine may be reduced by recirculating a portion of the engine's exhaust gas back to the engine cylinders. EGR may reduce harmful emissions from the machine by reducing the peak combustion temperature of the engine. Many diesel engines are coupled to an after-treatment system, which includes a diesel oxidation catalyst (“DOC”). The DOC may also be used to reduce emissions by controlling diesel particulate emissions and/or as an auxiliary catalyst for a filter in the after-treatment system, for example, a diesel particulate filter (“DPF”). Nevertheless, such systems often develop an accumulation of particulate matter (e.g., soot) on the filter, for example, due to low exhaust temperatures. The accumulation of particulate matter may result in increased back pressure on the prime mover. Accordingly, the drive system requires periodic regeneration, for example, to burn off particulate matter that has accumulated in the drive system. The regeneration may promote oxidation (e.g., burning off) of the particulate matter on the filter with heat from engine exhaust. However, under certain operating conditions (e.g., when environmental temperatures are low, when torque on the engine is low, etc.), an exhaust temperature of the engine may not be hot enough to provide regeneration. As a result, the machine may encounter difficulties in performing the regeneration in cold ambient temperature conditions (e.g., below freezing) and/or when there is a low load on the engine.
- U.S. Pat. No. 7,467,033, issued to Miller et al. on Dec. 16, 2008 (“the '033 patent), describes a method of controlling an engine to maintain a calibrated minimum load for the engine. The method of the '033 patent involves a minimum engine torque adder that is calibrate as a torque ramp rate to adjust the allowable torque limit that is added to the engine torque if the measured engine load is near the calibrated minimum engine load for a given engine speed. The method of the '033 patent may help to maintain engine fuel combustion stability and avoid undesirable engine exhaust gas temperatures during prolonged engine operation at low load. While the control method of the '033 patent may help maintain a calibrated minimum load on an engine, the added load on the engine via the torque added may not be desirable under certain conditions.
- The systems and methods of the present disclosure may address or solve one or more of the problems set forth above and/or other problems in the art. The scope of the current disclosure, however, is defined by the attached claims, and not by the ability to solve any specific problem.
- In one aspect, a hydraulic system for a machine may include an implement pump, a valve, and an implement valve subsystem. The implement pump may include a load sensing control, and the valve may control the flow of hydraulic fluid to the implement pump. The implement valve subsystem may include one or more implement control subsystems to control movement of an implement. The valve may be an electrohydraulic proportional relief valve and may include a solenoid configured to adjust the pressure of hydraulic fluid delivered to the implement pump proportionally to a current delivered through the solenoid.
- In another aspect, a method of operating a hydraulic system for a machine may include, in response to a regeneration cycle for a particulate filter in an after-treatment system for an engine, detecting one or more of an ambient temperature, a temperature of the exhaust of the engine, or a load demand on the engine. The method may also include, in response to one or more of the ambient temperature, the temperature of the exhaust of the engine, or the load demand on the engine being below respective threshold values, delivering current through a solenoid of an electrohydraulic valve. The electrohydraulic valve may control a flow of hydraulic fluid to an implement pump, and the current through the solenoid may cause the electrohydraulic valve to open and deliver hydraulic fluid to the implement pump to upstroke the implement pump. The implement pump may control an implement and may include a load sensing control configured to increase the pressure demand on the implement pump in response to the delivery of hydraulic fluid. The increase pressure demand on the implement pump may be configured to increase the power demand on the engine.
- In yet another aspect, an earthmoving machine may include an engine, an implement, and a hydraulic system. The hydraulic system may include an implement pump and an electrohydraulic valve. The implement pump may be powered by the engine and may be configured to drive the implement, and the implement pump may include a load sensing control. The electrohydraulic valve may control the flow of hydraulic fluid to the load sensing control of the implement pump. The electrohydraulic valve may include a solenoid configured to adjust the pressure of hydraulic fluid through the electrohydraulic valve proportionally to a current delivered through the solenoid.
- The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate various exemplary embodiments and together with the description, serve to explain the principles of the disclosure.
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FIG. 1 is an illustration of an exemplary machine according to aspects of the disclosure. -
FIG. 2 is a schematic of an exemplary hydraulic system of the machine ofFIG. 1 . -
FIG. 3 provides a flow chart depicting an exemplary method for controlling the hydraulic system of the machine. -
FIG. 4 provides a flow chart depicting an exemplary method for calibrating one or more aspects of the hydraulic system of the machine. -
FIG. 5 illustrates a graph of the current command and the power command formed during the calibration of one or more aspects of the hydraulic system of the machine. - Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the features, as claimed. As used herein, the terms “comprises,” “comprising,” “having,” “including,” or other variations thereof, are intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements, but may include other elements not expressly listed or inherent to such a process, method, article, or apparatus. Further, relative terms, such as, for example, “about,” “substantially,” “generally,” “approximately,” and “proximate” are used to indicate a possible variation of ±10% in a stated value.
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FIG. 1 depicts an exemplary machine, for example, awheel loader 10. Although the machine depicted inFIG. 1 is a wheel loader,wheel loader 10 may be any of the types of machines described above.Wheel loader 10 includes amachine body 12, which may include an operator station, an engine housing, and a prime mover or anengine 100.Engine 100 may be a diesel engine, and may be coupled to an after-treatment system 102. For example, an exhaust line fromengine 100 may be coupled to after-treatment system 102. After-treatment system 102 may include a diesel oxidation catalyst (“DOC”) 104 and a particulate filter 106 (e.g., a diesel particular filter or a DPF).Wheel loader 10 may also include animplement assembly 14.Implement assembly 14 may include anarm 16, alinkage 18, and abucket 20.Bucket 20 may be coupled to an end ofarm 16. Although not shown,bucket 20 may also be a different work implement, such as a fork, grapple, etc., and, in some aspects, the work implement may be interchangeable.Linkage 18 may have one or more degrees of freedom.Wheel loader 10 may include ground surface engaging devices, such aswheels 21 that supportmachine body 12 and are powered byengine 100. Although a wheeled machine is shown and described, one skilled in the art will appreciate that other machines, including track-type machines, may also be utilized.FIG. 1 also showswheel loader 10 with a first, lowered configuration (solid lines) of implementassembly 14 and with a second, raised configuration (dashed lines) ofimplement assembly 14. - In the example of the machine being
wheel loader 12, movement (e.g., lift) ofbucket 20 and/orarm 16 may be powered and controlled by alift actuator 22.Lift actuator 22 may include, for example, a hydraulic fluid cylinder actuator or any other type of actuator, as would be apparent to one skilled in the art. One or morelift pressure sensors 24 may be configured to measure forces within theactuator 22, or on another component oflift actuator 22, and may be force sensors. The tilt ofbucket 16 may be powered and controlled by atilt actuator 26.Tilt actuator 26 may include, for example, a hydraulic fluid cylinder actuator or any other type of actuator, as would be apparent to one skilled in the art. One or moretilt pressure sensors 28 may be configured to measure forces withintilt actuator 26, or on another component oftilt actuator 26, and may be force sensors. For example, as shown inFIG. 1 ,lift pressure sensors 24 andtilt pressure sensors 28 may be disposed in/on a head end and a rod end oflift actuator 22 andtilt actuator 26, respectively. Alternatively or additionally,lift pressure sensors 24 andtilt pressure sensors 28 may be disposed in other locations relative to an actuator, such as within a hydraulic circuit associated with an actuator (e.g., one or more ofcontrol subsystems 208 a-208 c,FIG. 2 ). Forces acting on lift and/ortilt cylinder pressure sensors 24 andtilt pressure sensors 28 may be configured to measure one or both of head-end and rod-end pressures of the lift and tilt cylinders, respectively. Alternatively,lift pressure sensors 24 andtilt pressure sensors 28 may be configured to measure a net force acting on a lift or tilt cylinder, respectively. Liftpressure sensors 24 andtilt pressure sensors 28 may detect pressure of fluid within their respective actuator. Force or pressure information may also be derived from other sources, including other sensors. - Additionally,
wheel loader 10 may include one or more additional sensors, for example, anarm position sensor 32 and abucket position sensor 34.Arm position sensor 32 may gather data indicative of a position ofarm 14, including for example, an angle, a height or an extension ofarm 14.Bucket position sensor 34 may gather data indicative of a position ofbucket 16, including, for example, a height, lateral location, and/or tilt ofbucket 16. Although not shown,wheel loader 10 may include one or more additional sensors, inertial measurement units, etc. - The sensors mentioned herein may be coupled, for example, via a wired or wireless connection, to a
controller 30. In these aspects,controller 30 may be in communication with one or more features ofwheel loader 10 and receive inputs from and send outputs to, for example, one or more user interfaces in the cab or remote fromwheel loader 10. For example,wheel loader 10 may include electrohydraulic and/or hydro mechanical hydraulic systems, andcontroller 30 may control one or more electrical switches or valves in order to control one or more hydraulic cylinders, actuators, or electrical elements in order to operatewheel loader 10. It is understood thatcontroller 30 may include one or more controllers each associated with one or more components or systems ofwheel loader 10. For example,controller 30 may be in communication with avalve 204 and/or an implement pump 206 (FIG. 2 ) for controlling aspects ofvalve 204 and/or implementpump 206, which may control aspects of engine 100 (e.g., a load command, a temperature of the output exhaust, etc.), as further detailed below. -
Engine 100 may be configured to generate and transmit power towheels 21, for example, via a transmission (not shown).Engine 100 may include an internal combustion engine that produces mechanical and/or electrical power output. For example,engine 100 may be a four-stroke diesel engine. In this aspect,engine 100 may be coupled to after-treatment system 102, which may include diesel oxidation catalyst (“DOC”) 104 andparticulate filter 106.Engine 100 may include one or more subsystems, for example, a fuel system, an air induction system, an exhaust system (coupled to after-treatment system 102), a lubrication system, a cooling system, and/or the like.Engine 100 may be configured to produce a torque output directed to a transmission and/or to other parasitic loads (e.g., to hydraulic systems (i.e., implement pump 206), electrical systems, cooling systems, etc.) through a range of speeds. - As mentioned,
engine 100 may be coupled to after-treatment system 102, which may includeDOC 104 andparticular filter 106.DOC 104 may be the first component (i.e., directly downstream from engine 100) of after-treatment system 102. For example,DOC 104 may receive an exhaust flow fromengine 100 at an inlet ofDOC 104.DOC 104 may be a flow through filter that includes one or more oxidation devices. The one or more oxidation devices may include one or more precious metals, and may help to initiate an oxidation of hydrocarbons, carbon monoxide, unburned fuel and oil, etc.Particulate filter 106 may be downstream of DOC in after-treatment system 102.Particulate filter 106 may be a wall-flow filter that helps to trap or otherwise collect soot or other particulate material that was not oxidized byDOC 104.Particulate filter 106 may be heated by the exhaust flow fromengine 100, thereby thermally aging or oxidizing the particulate matter deposited inparticulate filter 106 when the exhaust flow is of a sufficient temperature. In some instances, for example, when environmental temperatures are low, when torque on the engine is low, etc., the heat from the exhaust flow fromengine 100 may not be hot enough to oxidize the particulate material collected byparticulate filter 106. In these instances, it may be necessary forwheel loader 10 to perform a regeneration cycle to increase the load command onengine 100 such thatengine 100 outputs an exhaust flow that is hot enough to oxidize the particulate material (e.g., approximately 600 degrees Celsius). In some examples, although not shown, after-treatment system 102 may include a selective catalytic reducer (SCR), for example, downstream ofparticulate filter 106. -
FIG. 2 is a schematic illustration of a portion of ahydraulic system 200 that may control the position and/or movement of an implement, for example,bucket 16. As shown inFIG. 2 ,hydraulic system 200 includes apilot pressure valve 202, avalve 204, an implementpump 206, and an implementvalve subsystem 208.Hydraulic system 200 may include arelief valve 210, for example between portions ofvalve 204 and implementpump 206. For example,relief valve 210 may be a proportional relief valve, which may allow for the control of the pressure in the hydraulic line connecting adischarge line 206 a of implementpump 206 tovalve 204.Hydraulic system 200 may also include aresolver 212, for example, between portions ofvalve 204, implementpump 206, and implementvalve subsystem 208.Resolver 212 may include a hydraulic logic element and may help to maintain consistent pressures between portions, for example, pilot pressure portions, ofvalve 204, implementpump 206, and implementvalve subsystem 208 by receiving two pressures and outputting the higher of the two pressures.Hydraulic system 200 may also include amargin relief valve 214, which may be positioned within implementvalve subsystem 208, and may relieve pressure from implementvalve subsystem 208 when the hydraulic fluid exceeds a predetermined pressure.Margin relief valve 214 may help to create resistance to the flow of hydraulic fluid driven by implementpump 206. Furthermore,hydraulic system 200 may include one ormore pressure sensors 216, which may detect the pressure of the hydraulic fluid at one or more locations inhydraulic system 200. Moreover,hydraulic system 200 may include one ormore outlets 218, for example, to return hydraulic fluid to a reservoir tank. One or more components ofhydraulic system 200, for example, one or more ofpilot pressure valve 202, implementpump 206, implementvalve subsystem 208,relief valve 210,pressure sensor 216, etc., may be in communication (e.g., via a wired or wireless connection) withcontroller 30. -
Pilot pressure valve 202 may be any suitable pressure valve, such as, for example, a relief valve, a piston valve, a guided-piston relief valve, a differential-piston relief valve, etc.Pilot pressure valve 202 may provide a release of hydraulic fluid when the internal pressure ofhydraulic system 200 exceeds a pressure of approximately 2500 kPa to approximately 4000 kPa, for example, approximately 3800 kPa. Additionally,pilot pressure valve 202 may be coupled to one or more reservoirs (not shown) of hydraulic fluid. In one aspect,pilot pressure valve 202 may be configured to ensure an adjustable pilot pressure forhydraulic system 200, for example, controlled bycontroller 30. - As shown in
FIG. 2 ,valve 204 is a directional valve and includes asolenoid 230. For example,wheel loader 10 may be an electrohydraulic machine, andvalve 204 may be an electrohydraulic proportional valve.Valve 204 may be biased toward a closed configuration, butvalve 204 may open when current is delivered throughsolenoid 230.Valve 204 may be a proportional valve andsolenoid 230 may be a proportional solenoid, for example, such thatsolenoid 230 adjusts and/or regulates flow of hydraulic fluid throughvalve 204 based on an intensity of an electrical signal (i.e., current), for example, fromcontroller 30.Valve 204 may be a control valve associated withpump 206. Additionally, as shown,valve 204 may be upstream of implementpump 206, for example, such that output fluid fromvalve 204 may be delivered to pump 206, for example, throughresolver 212 when the pressure of the hydraulic fluid fromvalve 204 exceeds the pressure of hydraulic fluid on the opposing side ofresolver 212. - Implement
pump 206 may be a hydraulic pump and may include an integratedload sensing control 232. As mentioned, implementpump 206 may be powered byengine 100. Additionally, implementpump 206 may pressurize hydraulic fluid based on a pressure, volume, flow, etc. of hydraulic fluid received atload sensing control 232. In this aspect, the pressure command on implementpump 206 may be proportional to the current throughsolenoid 230, for example, through the relationship between the current throughsolenoid 230 and the flow of hydraulic fluid throughvalve 204. For example, as discussed below, over one or more ranges, the pressure command on implementpump 206 may be substantially linearly correlated to the current throughsolenoid 230. In these aspects,valve 204 andsolenoid 230 may be controlled to add load onengine 100, for example, during a regeneration cycle. Additionally, over the one or more ranges, the power command onengine 100 may be substantially linearly correlated to the current throughsolenoid 230. - Implement
valve subsystem 208 may include one or more subsystems, for example, to control the position ofbucket 20. The one or more subsystems may be controlled based on the relative pressures on respective portions of the subsystems. For example, implementvalve subsystem 208 may include a rack/dump control subsystem 208 a, a lift/lower/float control subsystem 208 b, and one or moreauxiliary control subsystems 208 c. Additionally, implementvalve subsystem 208 may include an implementvalve relief valve 220, which may be connected to anoutlet 222, for example, to return hydraulic fluid to the reservoir. -
FIG. 3 is a flow chart depicting anexemplary method 300 for controllinghydraulic system 200. In an optionalinitial step 302,wheel loader 10 may perform an operation, for example, moving material from one location to another. - Next, in a
step 304,wheel loader 10 may initiate a regeneration cycle or procedure. For example, one or more sensors coupled tocontroller 30 may detect a build up of particulate material onparticulate filter 106 in after-treatment system 102. Alternatively, the regeneration procedure may be initiated after a predetermined amount of operating time forwheel loader 10 since the previous regeneration procedure. As discussed above, the regeneration procedure includes increasing the load command onengine 100 such that the exhaust temperature is increased to a certain temperature and/or for a certain duration to help burn off the particulate material onparticulate filter 106 in after-treatment system 102. - A
step 306 may include increasing the load onengine 100 during the regeneration procedure by upstroking implementpump 206, for example, via one or more components ofhydraulic system 200. In this aspect,controller 30 may signalvalve 204 to transition from a closed configuration to a more open configuration, for example, by delivering current to solenoid 230. As discussed above, this current throughsolenoid 230 may deliver more hydraulic fluid to implementpump 206, which in turn causes implementpump 206 to pump hydraulic fluid at a higher pressure. Implementpump 206 pumping the hydraulic fluid at the higher pressure may increase the load demand onengine 100, asengine 100 powers implementpump 206. The increased load demand onengine 100 may increase the temperature of the exhaust output byengine 100, which may help to burn off particulate matter onparticulate filter 106 in after-treatment system 102. The hydraulic fluid pumped at the higher pressure by implementpump 206 is not used, for example, does not drive any components of implementvalve subsystem 208. Instead, as discussed below, the pressurized fluid may be released through one or more valves and return to a hydraulic fluid tank or reservoir (not shown). - In one aspect, step 306 may be optional. For example,
controller 30 may only signalvalve 204 to transition to the more open configuration when the temperature atparticulate filter 106 is below a certain threshold temperature. In this aspect,controller 30 may be coupled to a temperature sensor, for example, at an inlet ofparticulate filter 106. Alternatively or additionally,controller 30 may only signalvalve 204 to transition to the more open configuration when the ambient temperature is below a certain threshold temperature. In this aspect,controller 30 may be coupled to a temperature sensor on a portion ofwheel loader 10. Furthermore,controller 30 may be coupled to one or more oflift pressure sensor 24,tile pressure sensor 28,arm position sensor 32, and/orbucket position sensor 34.Controller 30 may receive one or more signals from these sensors indicative of a position and/or load ofbucket 20, which may be indicative of a pressure demand on implementpump 206 and/or a power demand onengine 100. In this aspect,controller 30 may only signalvalve 204 to transition to the more open configuration when one or more of the pressure demand on implementpump 206 and/or the power demand onengine 100 are below certain thresholds, for example, indicating low load conditions. - Then, a
step 308 includes ending the regeneration procedure. Ifstep 306 is performed,step 308 includes signalingvalve 204 to transition to a more closed configuration, for example, by delivering a lower current (or no current) throughsolenoid 230. - Lastly,
method 300 includes astep 310, in which wheelloader 10 returns to performing the operation (e.g., moving material). Step 310 may include indicating to the user that the regeneration procedure is complete. Nevertheless, it is noted thatwheel loader 10 may also be operated during the regeneration procedure. -
Method 300 may also include displaying one or more indications to a user, for example, via a user interface. For example, one or more the indications may indicate to the user that wheelloader 10 is undergoing a regeneration procedure, an estimated duration of the regeneration procedure, when the regeneration procedure is complete or nearing completion, etc. -
FIG. 4 is a flow chart depicting anexemplary method 400 for calibrating and/or mapping a relationship of components ofhydraulic system 200. For example,method 400 is a method for calibrating and/or mapping a relationship of a signal or current tovalve 204 relative to a pressure command on implementpump 206 and, correspondingly, a load command onengine 100.FIG. 5 is a graph of portions of the calibration duringmethod 400. - Although not shown,
method 400 may include an initial step of entering a calibration mode, for example, automatically and/or based on user input. The initial step of entering the calibration mode may be done after the manufacture ofwheel loader 10 and during initial calibration ofwheel loader 10, for example, before shipment to a user. Alternatively or additionally, the initial step of entering the calibration mode may be done whilewheel loader 10 is at a work site. In some aspects, various aspects ofmethod 400 may depend on the operational conditions ofwheel loader 10 and/or surroundingwheel loader 10, for example, ambient temperatures, work site elevation, bucket load conditions, engine speeds, etc. Astep 402 includes settingengine 100 at a first engine speed, for example, approximately 800 rotations per minute (“rpm”). Astep 404 then includes increasing (or ramping up) the current delivered tosolenoid 230, for example, to transitionvalve 204 to a more open position such that a greater amount of hydraulic fluid and/or a higher pressure of hydraulic fluid is delivered to implementpump 206. Step 404 may include increasing the current to solenoid 230 until a pump discharge pressure (e.g., as measured by pressure sensor 216) changes by a certain amount, for example, by approximately 100 kPa. The change in the pump discharge pressure may be indicative of the start of an active range forvalve 204, which may be a proportional EH valve. Nevertheless, the change in the pump discharge pressure may not yet indicate the active range over which the current to solenoid controls the overall load add control onengine 100. -
Method 400 further includes astep 406, in which the current to solenoid 230 is incrementally increased or ramped up. For example, the current to solenoid 230 may be increased by approximately 0.01 amps to approximately 0.02 amps, and may be held at each current level for a period of time, for example, approximately 5 seconds, approximately 10 seconds, approximately 20 seconds, approximately 30 seconds, etc. In one aspect, the current to solenoid 230 may be increased by approximately 5% to 10% of the previous current value. Each level of current to solenoid may yield a steady state pressure generated by the pump, which may be measured and recorded. The incremental increase in the current to solenoid 230 may be performed until the pressure change between consecutive current levels is less than a certain value (e.g., approximately 50 kPa). A pressure change between consecutive current levels being less than the certain value may be indicative of implementpump 206 reaching a maximum displacement. At the maximum displacement, the current command, the measured average pump pressure, and the actual engine speed may be recorded. - The current values and pressure values at the first engine speed may be correlated, for example, graphed, as discussed below with respect to
FIG. 5 . For example, the commanded current, actual average pump pressure while at the commanded current, and an actual average engine speed may all be recorded for each commanded current level to solenoid. Then, the output power (or power command on engine 100) may be calculated, for example, using the engine speed and pump pressure. In one aspect, the calculation may assume a pump speed to engine speed ratio and a maximum pump displacement based on various system and/or design parameters. A pump flow may be calculated based on the pump speed times the maximum pump displacement. The pump flow for a given situation may be calculated based on the pressure of hydraulic fluid indischarge line 206 a. For example: -
Pump Flow=Engine Speed×1.0448×Maximum Pump Displacement - The pump power may be calculated by the pump flow times the average pump pressure. In one example, the maximum pump power may equal the pump displacement of 165 cc/revolution times the average pump pressure of 8,000 kPa. Accordingly, if the engine speed is 800 rpm, the output engine power may calculated to be approximately 18 kW. It is noted that this calculation includes multiplying by 1.667×10−8 in order to convert to kilowatts. Alternatively, although not shown, instead of calculating pump power by multiplying the flow and pressure, the pump power may calculated by multiplying the torque and the shaft speed.
- Next,
method 400 includes astep 408, in whichengine 100 is set to a second engine speed, for example, approximately 1800 rpm. Then, step 406 may be repeated at the second engine speed as astep 410. For example, the current to solenoid 230 may be increased until a pump discharge pressure changes by a certain amount, for example, approximately 100 kPa. The change in the pump discharge pressure may be indicative of the start of an active range forvalve 204, which may be a proportional EH valve. Additionally, the current to solenoid 230 may then be incrementally increased or ramped up, and the pump discharge pressure at each level of current to solenoid 230 may yield a steady state pressure generated by the pump, which may be measured and recorded. Again, the maximum pump flow at the second engine speed may be calculated, and then the engine power may be calculated at the second engine speed. - As shown in
FIG. 5 , the measurements made during ofmethod 400 may be graphed as a current to power calibration curve. For example, the two sets of solenoid current commands and the calculated engine power commands (at the two different engine speeds) may be plotted on a graph (FIG. 5 ), andmethod 400 may extrapolate a line between the two points to create a current to power calibration curve. The current to power calibration curve may be used to correlate a current throughsolenoid 230 with a power command onengine 100, and thus a resulting temperature of the exhaust fromengine 100, which may help burn off particulate material onparticulate filter 106. It is noted that the measurements ofmethod 400 and graph ofFIG. 5 assumes a substantially linear relationship between the power of implementpump 206 and the current throughsolenoid 230. If other or additional components are used, this relationship may not be substantially linear. In this instance, the steps ofmethod 400 may be repeated, for example, in order to obtain additional data points (e.g., third and fourth data points). The data points on the graph of the current throughsolenoid 230 and the power of implementpump 206 may then be used to determine the relationship. In this aspect,method 400 may be repeated as many times as necessary to obtain data points and determine the relationship between the current throughsolenoid 230 and the power of implementpump 206. -
FIG. 5 illustrates agraph 500 of an exemplary relationship between the current command (e.g., in amps (“A”)) delivered tosolenoid 230 and the power command (i.e., in kilowatts (“kW”)) output byengine 100, for example, in order to power implementpump 206. The power command may be an additional power command relative to a baseline power command onengine 100, for example, under idling conditions. As shown, with 0 A delivered tosolenoid 230,engine 100 outputs a power command of 0 kW. As the current is increased, for example, to approximately 1.160 A, the power command increases, for example, to approximately 0.1 kW. This initial increase in power command relative to the increased current command may include a steep slope, as shown by aportion 502. - As discussed above,
portion 502 may correspond to step 404. Then, as the current is further increased, the increase in power command relative to the increased current command may include a slope that is less steep, as shown byportion 504. Overportion 504, at a first engine speed (e.g., 800 rpm), the current command may be increased from approximately 1.160 A to approximately 1.4 A, and the power command onengine 100 may be calculated based on the engine speed and the pressure of hydraulic fluid from implementpump 206. In this aspect, the power command onengine 100 may be approximately 45 kW. Then, the current command to solenoid 230 may be increased to approximately 1.9 A, and the resulting power command onengine 100 may be approximately 80 kW. However, further increasing the current command may not significantly increase the current throughsolenoid 230, and minimally increase the power command, for example, corresponding to the maximum pump flow. For example, as shown inFIG. 5 , the current command may remain at approximately 1.9 A, and the power command may be approximately 100 kW. This may be indicative of saturation of the current command at a configurable maximum current value, for example, as shown byportion 506 ofgraph 500. Alternatively or additionally, this may be indicative that implementpump 206 has reached maximum displacement, and thus that no additional power can be achieved. Furthermore, this may be indicative that the control valve output pressure has saturated or at a maximum value. As discussed above,portions -
Engine 100 may then be set to a second engine speed, for example, a maximum engine speed and/or approximately 1800 rpm, corresponding to step 408. Then, step 404 may be repeated, for example, asstep 410, and the current delivered to solenoid 230 may be incrementally increased until a pressure change between consecutive current values is less than a certain value. For example, step 410 may include setting the current command at approximately 1.29 A and measuring an engine command of approximately 18 kW. Moreover, setting the current command at approximately 1.56 A may result in a measured engine command of approximately 55.2 kW. These measurements may also be plotted ingraph 500. For example, as shown inFIG. 5 ,portion 504 may be substantially linear, illustrating the relationship between the current applied to solenoid 230 and the power command onengine 100 over this active range, corresponding to step 406 ofmethod 400. Additionally,graph 500 may be used to extrapolate a resulting power command onengine 100 for one or more current commands forsolenoid 230, which may also be used to increase the load onengine 100, for example, to help burn off particulate material onparticulate filter 106, to help in general retarding (e.g., whenwheel loader 10 is traveling down a hill), to help warm upengine 100 or other components ofwheel loader 10, for example, when startingwheel loader 10 in cold ambient temperatures, etc. Although the above current commands and power commands are discussed as a part ofgraph 500, it is noted that additional data points may be used to formgraph 500 or otherwise extrapolate a relationship of the current command and resulting power command under additional conditions, for different engine speeds, etc. Then, the calibrated relationship between the current commands and the power commands may be used, for example, inmethod 300, to help perform a regeneration procedure. Additionally, as mentioned above, one or more steps ofmethod 400 may be repeated in order to obtain additional measurements of the pressure changes between different current values, for example, in order to more accurately determine a correlation between the current throughsolenoid 230 and the power of implementpump 206. - Moreover, although not shown,
method 400 may be performed, andgraph 500 may be formed, in a reverse order. For example, for a first engine speed, a maximum current command may be applied to saturatesolenoid 230 with the maximum current, and the actual pump power may be calculated, indicative ofportion 506 as discussed above. Then, the current command may be incrementally reduced until the pump pressure decreases by a certain amount. The current command may be reduced further, and the actual pump power may be determined and plotted, as discussed above toform portion 504. Lastly, the current command may be reduced further (closer to 0 A), until the pump pressure decreases significantly, indicative ofportion 502. Then, these steps may be repeated at a second engine speed. In some instances, the pump pressure decrease may be observed afterengine 100 has been set to the second engine speed. The current commands on solenoid and resulting actual pump power onengine 100 may be graphed to form a graph similar tograph 500. - The disclosed aspects of
hydraulic system 200 of the present disclosure may be used in anywheel loader 10 or other machine having one or more hydraulic systems.Valve 204 may be incorporated intohydraulic system 200 with minimal modifications of existing hydraulic systems. Moreover, the delivery of hydraulic fluid fromvalve 204 to implementpump 206 causes implementpump 206 to upstroke without a pressure demand from implementvalve subsystem 208. Accordingly, the regeneration command, via implementpump 206, may require an increased load command on engine 100 (e.g., increasing the temperature of the exhaust fromengine 100 to increase the temperature at particulate filter 106) without an implement command. - As discussed above,
valve 204 may be an electrohydraulic valve withsolenoid 230. Usingvalve 204 to deliver hydraulic fluid to implementpump 206, for example, by applying current throughsolenoid 230, may cause implementpump 206 to upstroke and demand greater power fromengine 100, even though implementpump 206 or implementvalve 208 are not otherwise requesting greater power fromengine 100. Additional components ofhydraulic system 200, for example,margin relief valve 214, help to release or dump hydraulic fluid fromhydraulic system 200, which may help to reduce the overall pressure, generate a flow restriction for hydraulic fluid, and/or increase the pressure on implementpump 206 and the power demand onengine 100, without inadvertently delivering high pressure hydraulic fluid to implementvalve subsystem 208 orindividual subsystems 208 a-208 c. The pressure demand on implementpump 206, and thus the power demand onengine 100, may be proportional to the current applied throughsolenoid 230 ofvalve 204. Moreover, the increase power demand onengine 100 may increase the temperature of exhaust fromengine 100, which may help perform or expedite a regeneration cycle to burn off or otherwise remove particulate material onparticulate filter 106 of after-treatment system 102, for example, whenwheel loader 10 is in cold ambient temperature conditions and/or there is a low load onengine 100. Additionally, it is noted that the strategy to increase the power demand onengine 100 discussed herein may also be used in other circumstances. For instance, the strategy to increase the power demand onengine 100 may be used for general retarding, for example, whilewheel loader 10 is traversing a steep down grade and additional load onengine 100 is required. Furthermore, the strategy to increase the power demand onengine 100 may be used to help warm upengine 100 and/or other elements (e.g., hydraulic system 200) ofwheel loader 10, for example, when startingwheel loader 10 in cold ambient temperature conditions. - Furthermore, the calibration methods discussed herein may allow for a user and/or
controller 30 to extrapolate a relationship between current commands onsolenoid 230 and the resulting power command onengine 100. For example, as discussed above, within a determined range (i.e., portion 504), increasing the current throughsolenoid 230 increases the flow of hydraulic fluid to implementpump 206, which proportionally increases a pressure demand on implementpump 206, creating a proportional power command onengine 100. As a result, the temperature of exhaust output fromengine 100 may be increased without otherwise moving other components ofwheel loader 10. Moreover, this procedure may be performed bycontroller 30, thus reducing or eliminating a need for user intervention during a regeneration cycle. For example,controller 30 may determine the range ofportion 504.Controller 30 may then selectively deliver current throughsolenoid 230 during a regeneration cycle to control the output pressure of implementpump 206, and thus control the load demand onengine 100 and increase the temperature of exhaust output fromengine 100 during the regeneration cycle, for example, whenwheel loader 10 is in cold ambient temperature conditions and/or there is a low load onengine 100. Based on the calibration,controller 30 may deliver an appropriate or necessary amount of current to solenoid 230 to increase the power command onengine 100 as appropriate or needed, for example, in order to increase the temperature of the exhaust fromengine 100 and correspondingly increase the temperature atparticulate filter 106. As mentioned,controller 30 may be coupled to one or more temperature sensors, along withlift pressure sensor 24,tilt pressure sensor 28,arm position sensor 32,bucket position sensor 34, etc., and may thus determine when temperature and/or load conditions necessitate performingmethod 300 during a regeneration cycle. - It will be apparent to those skilled in the art that various modifications and variations can be made to the disclosed system without departing from the scope of the disclosure. Other embodiments of the disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. For example,
hydraulic system 200,method 300, andmethod 400 may be used on any machine having integrated hydraulic systems. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.
Claims (20)
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